#include	<signal.h>
#include <stdio.h>
#include <stdlib.h>  /* required by exit() */
#include <unistd.h>  /* required by pause()  */

static void	sig_usr(int);	/* one handler for both signals */
/* static tells that a function or data element is only known 
within the scope of the current compile. In addition, if you use 
the static keyword with a variable that is local to a function, 
it allows the last value of the variable to be preserved between 
successive calls to that function.
http://tigcc.ticalc.org/doc/keywords.html#static
*/

void  err_sys(char * msg) {
  printf("%s \n", msg);
  exit(-1); 
}

int main(void) {
	if (signal(SIGUSR1, sig_usr) == SIG_ERR)
		err_sys("can't catch SIGUSR1");
	if (signal(SIGUSR2, sig_usr) == SIG_ERR)
		err_sys("can't catch SIGUSR2");

	for ( ; ; )
		pause();
}

static void sig_usr(int signo) {		/* argument is signal number */
	if (signo == SIGUSR1)
		printf("received SIGUSR1\n");
	else if (signo == SIGUSR2)
		printf("received SIGUSR2\n");
	else
		err_sys("received unexpected signal");
	return;
}